Answer:
pKa = - 1.36012
Explanation:
∴ Ka = [H+] [A-] / [HA]
- % dissociates (%α) = ([A-] / [A-] + [HA])×100
∴ %α = 99.1%
∴ <em>C</em> HA = 0.21 M
Mass Balance:
⇒ <em>C </em>HA = [HA] + [A-] = 0.21 M............(1)
Charge balance:
⇒ [H+] = [A-] + [OH-].....[OH-] is neglected, it come from the water
⇒ [H+] = [A-]...............(2)
(2) in (1):
⇒ [HA] = 0.21 - [H+]
replacing in %α:
∴ %α = 99.1% = ([A-]/([A-]+[HA]))×100
⇒ 0.991 = [A-] / [A-] + [HA] = [A-] / 0.21 M
⇒ [A-] = (0.21 M)*(0.991) = 0.20811 M
Replacing in Ka:
⇒ Ka = [H+]² / (0.21 - [H+])
∴ [H+] = [A-] = 0.20811 M
⇒ Ka = (0.20811)² / (0.21 - 0.20811)
⇒ Ka = 22.9152
⇒ pKa = - Log (22.9152)
⇒ pKa = - 1.3601
Answer:
Measure liquid by aligning the meniscus with the volume line.
Explanation:
A pipette is an instrument specially made for measuring a small volume of liquid.
The pipette comes in various sizes to be used in measuring various volumes of liquid. Generally, the pipette has a volume line which helps us to measure a liquid.
A liquid is measured by aligning the meniscus with the volume line.
